The cerebellum is located behind the top part of the brain stem
The cerebellum receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements. The cerebellum coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity. It is also important for learning motor behaviors.
It is a relatively small portion of the brain -- about ten percent of the total weight, but it contains roughly half of the brain's neurons